1. Field of the Invention
The present invention relates to a method of processing electronic information, and also to a device for carrying out such a method. It is particularly, but not exclusively, concerned with a method of processing electronic information by modification of at least some of that information, such as modification of electronic documents prepared by word processor or modification of the source program for a computer.
2. Summary of the Prior Art
Several methods for processing electronic information have been proposed, which seek to control the modification of a source program of a computer, so as to prevent modifications which reduce the effectiveness of the source program. For example, in Japanese patent application No 63-80329 there was proposed a method of verifying a modification of a source program, in which the modified and unmodified source programs are compared. This method was particularly designed for error prevention during development of the source program. Also, in Japanese patent publication No 58-53377 there was proposed a method in which a record was made of which parts of the source program had been modified, and further modification of those already modified parts was limited, thereby limiting repeated modification of the program.
Furthermore, in the context of modifying electronic documents such as text or diagrams, it is known to provide a visual display of the modified document, for comparison with the unmodified document, either in printed form or in a display on a CRT (VDU).
It has been found, however, that the above methods of processing electronic information do not adequately control the modification of the information to prevent its effectiveness being reduced. For example, in Japanese 63-80329, the checking process is wholly automatic, and therefore the operator is given no warning when the proposed modification is unsatisfactory. In the method described in Japanese 58-53377, the control of modification is limited to those parts which have already been modified, and does not provide a general rule for controlling modification, irrespective of the previous history of modification.